Automatic safety switch



May 21, 1929. R. F. METCALFE AUTOMATIC SAFETY SWITCH Original Filed May 14, 1925 Patented May 21, 1929 UNITED STATES 1,713,773 PATENT OFFECE.

ROBERT F. METCALFE, OF BROOKLYN, NEW 'YORK, ASSIGNOR TO SOCONY BURNER CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

AUTOMATIC SAFETY SWITCH.

Original application filed May 14, 1925, Serial No. 30,312. Divided. and this application filed December This invention relates to an electric switch of novel construction. In particular the invention has to do with an improved automatic electric switch.

vided from my application for improvements in heating system and control therefor, S. N. 30,312, filed May 14, 1925.

WVhile the disclosure of this improved electric switch is made in the application for Letters Patent referred to as being employed or incorporated in a liquid fuel burner it is to be understood that the switch itself is capable of being employed in apparatus used for other purposes.

One of the features of this invention is to provide a switch which operates when a definite or predetermined pressure-0f fluid, such as a gas, is reached, or when the pressure of this fluid is reduced or falls from a normal predetermined value. Since the switch is adapted to be used in places where it is responsive to different conditions of pressure of a fluid, it will also be understood that it may be employed when the flow of fluids, either gas or liquid may be the operative force. In the instance where the flow of the fluid operates the switch, it will be noted that the rate of flow or the pressure resulting from the rate of flow, will operate the switch. The gas or liquid may be in actual contact with the switch or may operate an arm or other device which in turn operates the switch, but it will be recognized that the condition of flow or pressure of the gas or liquid is the cause of the operatidn of the switch for either 7 closing or opening the same. Thus, the fluid is in operative relation with the switch. In addition, it will be understood that the switch may be caused to open or close by reason of the expansion or contraction of a body of gas or liquid. Also, the switch may be operated by a rod moved by some force such as by the extension of a-bi-metallic rod due-t0 heat, or by reason of a mechanical movement of a rod responsive to an operation of some part of a machine in which the switch is incorporated. The particular incorporation of the switch herein referred to as employed in an oil burner, shows that the switch is re. sponsive to a pressure within the oil burner created by the burning of the oil. The switch in such an installation is constructed to move from its normalnatural position when com- Serial No. 77,323.

bustion takes place in the burner, and in such installation it automatically returns to its natural position when combustion in the oil burner ceases. The subject matter of this invention is di- The main object of this" invention is to provide an improved electric switch that is immediately responsive to changes in conditions in the apparatus in which it is incorporated, or is operated by some particular-portion of the apparatus.

A further object of the invention is to provide a novel electric switch which may be adjusted so that it will operate at different conditions of operation of the apparatus in which it is incorporated.

Another object of the invention is to provide such an improved electric switch as will automatically cause its contacts to be firmly brought into engagement when the switch assumes a predetermined position.

A further and particular object of this in vention is to provide an improved electric switch for use in oil burners, and to so construct the switch that it is immediately responsive to the conditions of burning or nonburning of fuel in the burner.

Other objects and advantages of the invention will be disclosed as the detail description below is read.

The preferred form of the invention is il lustrated in theaccompanying drawings wherein:

Fig. 1 is a front elevational view of the switch construction;

Fig. 2 is a sectional view' of the switch construction taken on the line 2-2 of Fig. 1; and

Fig. 3 is a sectional view taken on the line 3-3 of the switch illustrated in Fig. 1.

Referring now to the drawings wherein the preferred form of this switch is disclosed, there is shown a part or frame 95 of an oil burner 2. 'The frame and a portion of the burner are disclosed or referred to in the application for Letters Patent above mentioned. The frame 95 is provided with a suitable opening 96 in which there is placed a plate member 97 preferably pivoted at point 98.

-a suitable contact 35 which, in the installation noted in the application referred to, leads to a spark ignition circuit. On the front of the part 95 there is suitably attached a ring 99 which supports a frame or member 100 by preferably pivoting the same in the manner illustrated in the drawing. This frame 100 is provided with a projection 101 which carries a suitable roller 102, or engagement part, which in turn normally engages plate 97 It is desired that the member 100 be so pivoted that when hanging in its norinal natural position that it will force or bias the plate member 97 to one of its normal positions as illustrated in Fig. 2. On the lower end of frame 100 there is mounted an electrical contact 36 burner, it will be noted that when combustion takes place the pressure developed by reason of combustion causes the plate or plate member 97 to be oscillated about its pivot point 98, and the movement of this plate causes the member 100 to oscillate about its pivot point.

The ring 99 preferably carries an arm 105 of electrical conducting material, which arm is adapted to be engaged by a contact 84 carried by the frame 100. This exterior free end of arm 105 forms a contact 85 which is engaged by the contact 84. The contact 85 will be considered as a stationary contact.

Qther constructions for mounting this statlonary contact may be employed if desired. vIt will be seen that when combustion takes I place in the burner, cont-acts 84 and 85 will be brought into engagement for closing some particular electric circuit. At the same time contacts 35 and 36 will be opened or disen gaged. The opening of two contacts and the closing of two others when the switch is moved in response to a predetermined pressure is readily accom lished'by reason of pivoting the plate mem er 97 at its base while frame or member 100 is pivoted at a point substantially opposite to the pivot point of the plate 97.

Suitable electrical flexible conductors are illustrated as being connected to the various contacts in this type of switch construction. These conductors may be varied as desired in respect to their forms and locations. The preferred construction of this switch as herein illustrated functions tobe instantaneously responsive to the beginning of combustion and to the cessation of combustion.

Suitable means for adjusting the switch so that it may respond to different predetermined pressures may be employed as desired. In this instance, the adjustable means is provided in the form of a weight 82 which may be moved back and forth on a screw threaded rod 104. Thus the response of the movement of the plate member 97 may be varied as desired. 7

While there is herein disclosed the fact that plate member 97 is responsive to a particular pressure of a fluid within the oil burner, it will be understood in the broad conception of the invention that theplate member 97 may be of any particular shape or form which is responsive to a pressure, be that pressure exerted by a gas itself or by a container for the gas or by a thermostatic element responsive to temperature conditions. Since the frame 95 is provided with the opening 96 it will be seen that such construction may be incorporated in the channel through which a fluid or liquid flows, such for instance, as placing thisswitch in a pipe conducting oil. The plate 97 would be of proper size to permit oil to flow around the exterior thereof or through restricted perforations in the plate, but should the rate of flow of the oil increase a material extent, the pressure resulting from this rate of flow against the plate member 97 would cause it to be oscillated about its pivot point thereby oscillating the switch to open contacts 35 and 36 and to close contacts 84 and 85. If desired this improved type of switch may only carry two of the contacts which may be positioned to be brought into engagement either upon the outward movement of the switch elements or upon the return of the switch elements to their natural positions. The preferred form of adjusting the switch it will be noted, will operate to make the switch responsive to any predetermined desired value of pressure. Thus the switch is capable of adjustment so that it will be responsive to conditions under which the switch is installed.

It will be seen from the foregoing description that a novel form of electric switch and the operation thereof have been disclosed. It

is to be noted that the switch may be auto-,

matically operated by any suitable functioning element, such as an expanding or flowing gas or liquid, or the pressure developed -in each gas or liquid. Also it will be seen that the switch is capable of being operated by an arm or lever responding to any particular function of the apparatus in which the switch is incorporated. Another feature is that the construction of the switch is such that the switch is naturally biased to one of its normal positions.

It will be understood that while I have herein described in detail a particular embodiment of my invention for purposes of full disclosures, and some detailed features which I am specifically claiming for a. special adsaid first contact when a contact carried by vantage, many changes and modifications may be made in the particular construction and arrangement of parts without departing from the broad scope of my invention which is outlined in the sub-joined claims.

I claim as my invention:

1. In an electric switch the combinationof a stationary contact, a plate pivoted at its lower end and adapted to be oscillated. from its normal position" when a predetermined pressure of a fluid in operative relation with said plate exists, a frame pivoted opposite to the pivot point of said plate and being mounted to engage said'plate and to be oscillated thereby when said plate is oscillated, and said frame and adapted to engage said stationary contact when said plate is oscillated.

In an electric switch'the combination of a stationary contact, a plate pivoted at its lower end and adapted to be'oscillated from its normal pressure of a fluid in operative relation with Said plate exists, a frame pivoted opposite to the pivot point of said plate and being constructed to engage said plate and to be oscillated thereby when said plate is oscillated, a contact carried by said frame and adapted to engage said stationary contact when said plate is oscillated, and means for adjusting said switch so that said plate will be oscillated at predetermined pressures.

3. In an electric switch the combination or" a plate member adapted to be responsive to a predetermined pressure of a fluid in operative relation therewith, an electrical contact carried by said plate member, a second member positioned to normally engage said plate member and to be moved thereby, and an electrical contact carried by said second member and adapted to be brought into engagement with said first contact when said members are in predetermined relative positions.

4. In an electric switch the combination of a plate member adapted to be responsive to a predetermined pressure of a fluid in operative relation therewith, an electrical contact carried by said plate member, a second member positioned to normally engage said: plate member and to be moved thereby, an electrical contact carried by said second member and adapted to be brought into engagement with said members are in predetermined relative positions, and means for adjusting said switch for varying the time of its operation.

5. In an electric switch the combination of a fpivoted plate member adapted to beescillated in response to the pressure of a fluid in operative relation therewith, an electrical contact carried by said plate member, a second pivoted member adapted to normally be in engagement with said plate member, an electrical contact carried by said second member and being so positioned as to be more firmly position when a predetermined brought into engagement with said first contact as said members approach their natural positions.

6. In an electric switch the combination of a plate member pivoted at its base, a contact carried by said plate member and positioned at right angles to the plate, a second member pivoted substantially opposite to the pivot point of said plate member, said second member having a part thereof in engagement with said plate member, an electrical contact carried by the lower end of said second member and adapted to be brought into engagement with said first cont-act with a varying degree of pressure as said members approach their natural positions.

7. In an electric switch the combination of I a plate member adapted to be oscillated by a predetermined pressure of fluid in operative relation therewith, a second member so mounted as to engage said'plate member and to normally force said plate member to its normal natural position, and electrical contacts, carried by said plate member and by said second member and adapted to be brought into engagement as said members approach their natural positions.

8. In an electric switch the combination of a plate member adapted to be oscillated by a predetermined pressure of-fiuid in operative relation therewith, a second member so mounted as to engage said plate'member and to normally force said plate member to its normal natural position, electrical contacts carried by said plate member and by said second member and adapted to be brought into engagement as said members approach their natural positions, and means for adjusting said switch so that said plate hnay be oscillated at predetermined pressures.

9. In an electric switch thecombination of a stationary electrical contact, a plate member adapted to be moved in response to a predetermined pressure or" a fluid in opera-, tive relation therewith, a second member mounted to normally engage said plate member, an electrical contact carried by said second member for engagement with said stationary contact when said members are moved, and two other'electrical contacts one of which is carried by said plate member and the other carried by said second member, said last named contacts adapted to be brought into engagement when said members are in their normal natural positions.

10. In an electric switch the combination of a stationary electrical contact, a plate member adapted to be moved in response to a predetermined pressure of a fluid in operative relation therewith, a second member mounted to normally engage said plate memher, an electrical contact carried by said second member for engagement with said sta tionary contact when said members are moved, two other electrical contacts one of which is carried by said plate member and the other carried by said second member, said last named contacts adapted to be brought into engagement when said members are in 5 their normal natural positions, and means for adjusting said switch to have it respond to a desired pressure of'the fluid.

11'. In an electric switch the combination of a stationary contact, a plate member pivoted at its base and adapted to be oscillated by a predetermined pressure-of a fluid in operative relation therewith, an electrical contact carried by said plate member, a second member pivoted at a point substantially 15 opposite the pivot point of said plate member, said mally in engagement with said plate member'and to bias the same to a normal natural position, two electrical contacts carried by said second member, one of said contacts adapted to engage the contact carried by said plate member when said members are in their natural positions, the second contact on said second member adapted to engage said stationary contact when said plate member and second member have been moved to their pressure responsive positions.

This specification signed this 21st day of December, 1925. 1 ROBERT F. METCALFE.

second member adapted to be nor- 

